A British warship slips across a darkening sea at the start of Chris Ryan's Strike Back (Sky 1). Below deck, an elite special-forces team prepares for a daring raid. Hard men try to outstare each other, to find out who's the hardest. Then they look at photos of their families, maybe for the last time.

We're in the Persian Gulf, it says on the screen. It's 18 March 2003 – 24 hours before the invasion of Iraq. The writing is in an old-fashioned typewriter font: basic, distressed. I reckon Chis Ryan writes in this font, bashing it out on the keyboard, rat-a-tat-tat. He probably has headphones on, and listens to speed metal while he writes, to get into the zone. Before that, he has smashed down the door to his study, dived into room, and rolled across the floor to his desk. Go go go!

Ryan – not his real name – was the only member of the first gulf war's Bravo Two Zero mission to escape. Since leaving the SAS, he has written several books, including the novel that this is based on. The intel's been gathered, the lads go in, take out the enemy and rescue a British businessman who has been held hostage. But the man in charge, played by Richard Armitage, screws up. He forgets that if you shoot a suicide bomber clean in the head then that will stop the reflex release of the "dead man's trigger" and the bomb won't go off. (Is that true? That's so interesting.)

Two men are lost, another is brain-damaged, and Armitage resigns. Out on his arse and down on his luck, he's now a security guard in London. Next stop the Embankment and a serious drug habit. But an extraorinary series of coincidences conspire to put him back in Basra, to strike back – at the enemy, and at the demons within. There are old scores to settle, debts of honour to be repaid, revenge to be taken, Who Dares Wins, all of that. Oh, but first the authorities have to address our hero's mission-limiting self-esteem issues, which are compounded by a fixation on physical and sexual inadequacy. They assign a Section 20 special female operative from MI6 to pose as a doctor, pretend to find him irresistible and, well, give him a free shag basically, on the MoD.

Does that really happen? God, what kind of pathetic male fantasy is this? Kit off, get down, go, go, go. Kit on, get down, go, go, go. Who is this for? The kind of sad men who know their IOCs from the IEDs, who like to dress up and play soldiers at weekends because they haven't got girlfriends. And me. I quite enjoyed it, I'm embarrassed to say. And I have to say too, otherwise Chris Ryan will TAKE ME DOWN.

Here's another vessel at sea. Not a warship, but the Princess Matilda. And who knows exactly where it is, because this is Timothy Spall: Somewhere At Sea (BBC4). He describes himself as an "idiot mariner", but feels likes Marco Polo, he says. Four years ago, the actor and his wife, Shane, set off from London in their boat, named after their granddaughter. It was a present to himself, for getting through leukemia. They are in no particular hurry, and have only got as far as Cornwall.

Boaty people tend to be terribly tedious, I find, but the Spalls are delightful. Not many yachtsmen can act out the Beaufort scale so entertainingly. "Force 10, very high breaking waves, dense foam streaks," he shrieks, dense foam streaks flying from his own mouth. Not that Spall is really a yachtsman: the Matilda is a Dutch barge, specially converted and very comfortable it looks too, with bookshelves and a cosy wood-burning stove.

He's not exactly very special services either. It's more a case of: Who Doesn't Dare Doesn't Even Set Off. They spend the best part of a year in the Helford river, waiting for the weather to clear up before plucking up courage to attempt a rounding of the treacherous Lizard Point. "If in doubt, don't set off," Spall says, studying the book that shows all the tidal streams that flow round the Lizard. It's probably just as well: he's on the wrong page. That's not the Lizard, Tim, it's Portland Bill, which you must have already passed to get where you are now – but maybe you didn't even notice it.